POS0690 IN AXIAL SPONDYLOARTHRITIS, NON-STEROIDAL ANTI-INFLAMMATORY DRUGS REDUCE MRI-APPEARANCE OF SACROILIITIS
Authors: G. Jones, A. Bennett, R. Sengupta, P. Machado, H. Marzo-Ortega, L. Aucott, G. Macfarlane
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> MRI evidence of active sacroiliitis (sacroiliac joint bone marrow oedema (BMO)) is commonly used to assist diagnosis and classification of axial spondyloarthritis (axSpA). Non-steroidal anti-inflammatory drugs (NSAIDs) are used as first-line therapy, and for persistent clinical symptoms continuous treatment is recommended. Prescribed in primary care, and widely available over-the-counter, many patients are already taking NSAIDs when they first present to rheumatology. <h3>Objectives</h3> To determine whether NSAID use leads to an underestimation of sacroiliac joint BMO. <h3>Methods</h3> Adults with axSpA were recruited from NHS rheumatology clinics and asked to discontinue their NSAIDs for 1-2wks before undergoing a sacroiliac joint MRI (Scan 1) using a standardised protocol. All participants then re-started their NSAIDs. Those who scanned positive for BMO lesions, as determined using internationally recognised (ASAS) definitions, underwent a second scan 6wks after restarting NSAIDs. Scans were read independently by 2 readers (adjudicated by a 3rd, if required), blinded to participants' clinical characteristics and timepoint. We determined the proportion of participants who scanned negative at Scan 2 (on NSAIDs) who had previously scanned positive at Scan 1 (off NSAIDs). <h3>Results</h3> 311 participants were recruited from 34 centres. Table 1 shows participants' baseline characteristics. Almost all participants (296; 95%) completed the NSAID washout and underwent Scan 1. However, 135 (50%) reported an increase in spinal pain (median increase: 2 points on a 0-10 numerical rating scale; inter-quartile range: 1-3), and 166 (61%) reported worsening of disease activity (median increase in BASDAI: 0.9; 0.5-1.6). At Scan 1, 149 (50%) were positive for BMO lesions. 131 (88%) participants underwent the six-week follow-up scan, of whom 31 scanned negative (24%; 95%CI: 17-32%). <h3>Conclusion</h3> These findings suggest that NSAIDs influence sacroiliac BMO and, where sacroiliitis is present, around one-in-four show resolution of lesions in the presence of NSAIDs. This has important implications for axSpA diagnosis and classification. If patients with axSpA (or suspected axSpA) are willing to attempt NSAID washout prior to MRI, this should be considered. There may be concerns about increases in disease activity or spinal pain, but we also provide evidence that almost all patients who attempt washout can successfully achieve it. <h3>Acknowledgements</h3> The study was funded by Versus Arthritis (ref: 21022) <h3>Disclosure of Interests</h3> Gareth Jones Speakers bureau: Janssen, Grant/research support from: Pfizer, AbbVie, UCB, Amgen, Alexander Bennett Speakers bureau: AbbVie, Biogen, Novartis, Pfizer, UCB, Consultant of: Abbvie, Eli Lilly, MSD, Novartis, Pfizer, UCB., Grant/research support from: Pfizer, Raj Sengupta Speakers bureau: AbbVie, Biogen, Celgene, Eli Lilly, Novartis, Pfizer, UCB, Consultant of: AbbVie, Biogen, Eli Lilly, Novartis, Pfizer, UCB, Grant/research support from: AbbVie, Celgene, Novartis, UCB, Pedro Machado Speakers bureau: AbbVie, BMS, Celgene, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Orphazyme, Pfizer, Roche, UCB, Helena Marzo-Ortega Speakers bureau: AbbVie, Biogen, Celgene, Eli Lilly, Janssen, Novartis, Pfizer, Takeda, UCB, Consultant of: Eli Lilly, Janssen, MoonLake, Novartis, Pfizer, UCB, Grant/research support from: Janssen, Novartis, UCB, Lorna Aucott: None declared, Gary Macfarlane Grant/research support from: Pfizer, AbbVie, UCB, Amgen.